[teresap]

2018 colorado z71. Purchased new 2/25/18. All great until this summer when service 4wd light came on. Searched threads and decided it was not urgent to take in (1.5 hrs away to service). In August of 2022, battery was dead at 70k miles, so replaced it. In October, battery was low and barely started, so took it back where I purchased battery and they said it may have been a bad battery, so replaced it again. I began to monitor voltage on display, and it was dropping every night, generally in the 11.7 v range. Called Ford dealer in my town in early November to see if they could track down the battery draw, and check out service 4wd light… (remember chevy dealer is 1.5 hrs away and we were hammered with snow and ice). They said they could do it, found a c0321 code and said I needed a new transfercase motor. Could not find the battery drawdown. Fast forward to christmas, and battery voltage at 11.5, 11.3, 10.7, so was able to get it into chevy dealer on 12/30. Every day he tested, and could not find a draw or spike until he touched wires at the x101 block near battery case. Found a spike somewhere there at .8 amp draw. Could not get it to do it again though. Service 4wd light went off, and battery is not drawing down as much for sure. Yesterday it was 12v, day before it was 11.8. He said he found two codes in history, one relating to engine and one to lighting (c0321 and I don’t know the other code). He believes it was unnecessary of Ford to have replaced transfercase motor, as finding two codes in history would have you believe more than the transfercase motor was an issue. We have never had any issues going in and out of 4wd, and use it during snow or in various mountain/soft conditions. I am a total blank stare when it comes to anything under the hood, so be nice. Or patient. Or at least not an AH and I don‘t mean amp hour😬…Any advice?

 

[GraniteBlue05]

Well . . first. . did you try putting a trickle charger on it over night or a battery maintainer?
Why let it drain down to the point it won't start?
While necessary to find the current drain. . . it isn't doing the battery nor the rest of the electronics in the truck any good by depriving them of proper battery voltage.

What did the DIC show for battery voltage when the engine was running and alternator charging?

 

[Tpustejo]

I did not trickle charge or anything else. It shows 14.5 when running.

 

[Beadblaster]

I am dealingvwith a co321-04 code as well as a current draw also. C0321 has something to do with tranfer case motor wiring to the motor. I have no 4 wd and the shift motor does not work.I am getting a new motor tomorrow so I will see if that fixes the transfer case issue. C0321
DTC C0321 01 : Range Actuator Lock Control Circuit Short to Battery
DTC C0321 02 : Range Actuator Lock Control Circuit Short to Ground
DTC C0321 04 : Range Actuator Lock Control Circuit Open
Not sure with the circuit being open if that would be the draw.

 

[teresap]

Thanks. I hope it works for you. It has been a real booger to track down. Chevy mechanic told me it is likely the service 4wd light will come back on, but he now may be able to pinpoint it if/when it returns. I will see if he can get me the other code.

 

[Beadblaster]

Did your 4wd work when you had those codes?

 

[teresap]

4wd has always worked.